Fluorosilicon compounds and preparation method

ABSTRACT

A fluorinated organosilicon compound is represented by formula (I). ##STR1##

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to fluorosilicon compounds and to a preparationmethod.

2. Description of the Prior Art

The majority of known fluorinated organosilicon compounds havestructures in which a fluorine-containing groups such as perfluoroalkylis bonded to a silicon atom through a dimethylene or trimethylene group.Synthesis of these compounds usually requires many stages, including aGrignard reaction and a reaction involving a precious metal catalyst,such as platinum (cf. U.S. Pat. No. 5,202,453; EP 0,538,061 A2).Reactions for making fluorinated organosilicon compounds by way of acyclization process between olefine derivatives of silicone and fluorinehave also been described (cf. U.S. Pat. No. 2,596,967; UKP 760,201 and802,358; Holbrook G. W. J. Am.Chem.Soc 82 825 (1960); Park J. D. J.Org.Chem., 25, 1628 (1960). However, this reaction has been largelyignored over the past ten years.

SUMMARY OF THE INVENTION

According to the first aspect of the invention there is provided afluorinated organosilicon compound represented by the formula: ##STR2##Preferably the compound is represented by the following formula:##STR3## wherein R¹, R², R³ and R⁴ are independently selected from alkylgroups having 1-4 carbon atoms or independently selected from the abovealkyl groups,the CF₃ CH₂ CH₂ -- group, and the R⁶ (R⁵)_(c) (CF₂ CF₂O)_(b) CFCF₂ CH₂ CH -- group, where R⁶, R⁵, a,b and c are as hereinafterdefined. R⁵ is a bivalent group such as --OCF₂ --, --OCF₂ CF₂,-- or--OCF₂ CF(CF₃)--. R⁶ is a --OCF₃ -- group or --F atom. a is an integerfrom 0 to 6, b is zero or 1, c is an integer between 2 and 6.

Fluorinated organosilicon compounds in accordance with the inventionhave a wide operating temperature range and excellent chemicalresistance; they are oil- and water- repellent and have outstandingdielectric properties. In addition, due to the phenomenon of"super-flexibility", the viscosity of these materials is much lower thantheir molecular weight would suggest. All these properties, togetherwith their density, which can be arranged to be in the range 1.3-1.7g/ml make these liquids very suitable for use as base liquids inElectro-Rheological (ER) Fluids as well as more general applications.

The invention includes a cyclo butane ring of formula: ##STR4##

A preferrred formula being: ##STR5##

According to a second aspect of the invention, there is provided amethod of manufacturing a compound in accordance with the first aspectby reacting a vinyl siloxane of general formula: ##STR6## wherein R¹,R², R³,and R⁴ have the meanings defined above, with a perfluoro-olefinof the general formula:

    CF.sub.2 ═CF(OCF.sub.2 CF.sub.2).sub.b (R.sup.5).sub.c R.sup.6

wherein R⁵, R⁶, b and c are as previously defined above, in the presentof a free radical inhibitor.

The compounds are produced by a reaction between vinyl siloxane andperfluoro-olefin in the presence of a free radical inhibitor at elevatedtemperature and pressure.

Preferably, in the cyclization reaction of the vinylsiloxane and theperfluoro-olefin, the ratio of reactants is in the range 1-2 moles ofperfluoro-olefin for each mole of vinyl siloxane, preferably between 1.1and 1.6. The reaction temperature may be in the range 150-250° C. andpreferably between 180 and 230° C. The reaction time may be 5-100 hours,and typically between 10 and 70 hours. The reaction is preferablycarried out at elevated pressure in an autoclave.

Typical examples of fluorinated organosilicon compounds prepared by thismethod include: ##STR7##

I claim:
 1. Fluorinated organosilcon compounds having at least onecyclobutane ring connected with fluoro contained groups through oxygenatom, the compounds being represented by the formula wherein R¹, R², R³,and R⁴ are independently selected from alkyl groups having 1-4 carbonatoms, the CF₃ CH₂ CH₂ -- group, the CH₂ ═CH-- and the ##STR8## R⁵ is abivalent group selected from --OCF₂ --, --OCF₂ CF₂ --, --OCF₂ CF(CF₃)--₇R⁶ is a CF₃ O-- group or a C₃ F₇ O-- group attached to the terminatedcarbon atom of the R⁵ group, a is an integer from 0 to 6, b is zero or1, c is an integer between 1 and
 6. 2. A compound as claimed in claim 1,having the formula: ##STR9##
 3. A compound as claimed in claim 1 havingthe formula:
 4. A compound as claimed in claim 1 having the formula: 5.A method of manufacturing a compound as defined in any one of claims 1to 4 by reacting a vinyl siloxane of general formula wherein R¹, R², R³,R⁴ and a are as defined in claim 1, with a perfluoro-olefin of generalformula:

    CF.sub.2 ═CF(OCF.sub.2 CF.sub.2).sub.b (R.sup.5).sub.c R.sup.6

wherein R⁵, R⁶, b and c are as defined in claim 1, in the presence of afree radical inhibitor.
 6. A method as claimed in claim 5, wherein theratio of reactants is in the range 1N to 2N moles of perfluoro-olefinfor each mole of vinyl siloxane, preferably between 1.1 N and 1.6N,where N is the number of vinyl groups on a single molecule of the vinylsiloxane.
 7. A method as claimed in claim 5, wherein the reaction iscarried out at a temperature range 120-250° C. and preferably between150 and 200° C.
 8. A method as claimed in any one of claim 5, whereinthe reaction is carried out over the time period of 5-100 hours, andpreferably between 10 and 70 hours.
 9. A method as claimed in any one ofclaim 5, wherein the reaction is carried out at elevated pressure. 10.An electro-rheological fluid having as its base liquid a compound asdefined in any one of claims 1 to 4, or a mixture of such compound withother fluorine-containing compounds.